This invention relates generally to plastic conveyor belts, typically used in the food industry. More specifically the invention is concerned with belts made up of plastic interdigited modules connected by transverse rods, and with an improvement whereby the modules or some of the modules can be readily converted to support rollers in order to reduce back pressure of items carried on the conveyor.
Examples of plastic conveyor belts having interdigited modules are shown in U.S. Pat. Nos. 4,472,907, 4,949,838 and 4,993,554, as well as in application Ser. No. 594,623 referenced above. Accumulation-type or low back pressure-type conveyors are shown in U.S. Pat. Nos. 4,231,469, 4,821,869 and 4,909,380. The referenced '469 patent shows a low back pressure-type conveyor having connecting rods which secure the modules together and also serve to support rollers positioned at spaced locations on the rods. However, unlike the belt system of the present invention, in that patent (FIG. 7) the projections from module to module were not interdigited in alternating arrangement but instead had a pair of projections from one module positioned between a wider-spaced pair of projections from the next module. A roller was then positioned between the inner ones of these four projections. In addition, the accumulating belt of that patent was not capable of travel around curves, as opposed to one embodiment of the present invention.
It is a primary purpose of the present invention to provide a modular plastic conveyor belt system wherein accumulation rollers can be easily added at selected positions in situations where low back pressure is desired, supported by the connecting rods, and without modifying the basic modules or affecting the integrity of the conveyor belt.